/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.streaming.api.windowing.assigners;

import org.apache.flink.annotation.PublicEvolving;

import java.io.Serializable;

/**
 * A {@code SessionWindowTimeGapExtractor} extracts session time gaps for Dynamic Session Window Assigners.
 *
 * @param <T> The type of elements that this {@code SessionWindowTimeGapExtractor} can extract session time gaps from.
 */
@PublicEvolving
public interface SessionWindowTimeGapExtractor<T> extends Serializable {
	/**
	 * Extracts the session time gap.
	 * @param element The input element.
	 * @return The session time gap in milliseconds.
	 */
	long extract(T element);
}
